Ultra-fast quenching devices are necessary for rapidly cooling or quenching semiconductor material when it is annealed. Temperature uniformity across the surface of the material as it is quenched is also an important requirement. For example, rapid changes in temperature are necessary for achieving enhanced properties during the annealing process of gallium arsenide (GaAs) wafers. During this process, GaAs wafers are typically heated using high intensity light sources. The rate of heating is varied by adjusting the source intensity and by optically concentrating the radiation. After heating the wafers, the wafers are then quenched to limit and maintain control of the concentration of defects found in GaAs and to fix desirable crystal structure not obtainable by normal cooling at ambient temperature.
There are several methods available for quenching GaAs wafers as well as other semiconductor materials during the annealing process. One method of quenching includes cooling by radiation. The problem with this method of cooling is that the rate of radiation cooling for temperatures above several hundred degrees Celcius is mostly dependent on the temperature of the material and its surface area being cooled and cannot be accelerated appreciably by lowering the temperature below normal manufacturing ambients. The material also cools unevenly, since the edges of the material cool more rapidly than its center. Other methods of cooling such as conductive and convective cooling have been found to be less uniform than radiation cooling because of the problem of controlling the effect of the coolant over the surface of the material.